Is it ensure, insure, or assure?
1610s, Mohammed, Arabic masc. proper name, literally "the Praiseworthy," name of the prophet of Islam (c.570-632). The earliest forms of his name in English were Mahum, Mahimet (c.1200); originally also used confusedly for "an idol." Wyclif has Macamethe (c.1380), and Makomete also turns up in 14c. documents. Mahomet was common until 19c.; cf. Mohammed.